Drug abusers and/or addicts are known to take a dosage form containing an opioid analgesic, such as oxycodone, morphine or methadone, and crush, shear, grind, chew or dissolve it in water or in alcohol, and either heat it or make it cold in order to subsequently extract the opioid component from the mixture.
The extract, having a significant amount or even an entire amount of the drug, becomes available for immediate absorption by 1) injection, 2) inhalation, or 3) oral consumption.
The use of gel-forming or viscosity increasing agents (e.g. polyvinyl alcohol, HPMC, polyethylene oxide, etc.) to prevent extraction of opioids from solid dosage pharmaceutical preparations is known in the art. In addition, nasal tissue irritants such as sodium lauryl sulfate have been used to deter extraction of active drugs. Alternatively, emetic agents (such as zinc sulfate) as well as pharmaceutical formulations containing an opioid agonist, opioid antagonist or a bittering agent (a bitter chemical used as an aversive agent) have also been evaluated (Kumar et al., 2007, Palermo et al., 2001, Kaiko et al., 2001, Oshlack et al., 2003) to decrease the extractability of drugs such as methadone.
United States Patent Publication 2006/0104909 (Vaghefi et al.) provides examples of abuse-resistant, controlled-release pharmaceutical compositions in which an effective amount of an active compound is wetted with a coating material or distributed throughout a matrix that is insoluble in water and non-erodable at a pH less than about 6. Examples of gel forming polymers or viscosity increasing agents to prevent filtration are known: see, for example, United States Patent Publication No. 2007/0264327 (Acura Pharmaceuticals). Importantly, these examples are used for extended-, controlled- or slow-release pharmaceutical products, where the active pharmaceutical ingredient is released slowly from the composition over an extended period of time (i.e., 8-24 hours).
There remains a need for new formulations that make it difficult, if not impossible, for individuals to extract drugs, such as methadone, from pharmaceutical products in order to reduce the potential for drug abuse. In particular, new formulations are needed which can be used with immediate release pharmaceutical products. Of significant interest are formulations which contain methadone.
New formulations, while having abuse-resistant properties, must allow for the active pharmaceutical ingredient to be soluble in the gastrointestinal tract and have a desired pharmacological activity. In the case of opioids, the pharmacological activity would be an analgesic effect.